Coarticulation in apraxia of speech: an acoustic study of non-words

Authors : Sandra P Whiteside and Rosemary A. Varley

What is apraxia of speech?•Apraxia of speech is a motor speech

disorder which results from lesion of the language dominant hemisphere in the region of frontal pre-motor cortex (Whiteside, & Varley, 1998).

•In other words, apraxia of speech is a motor speech disorder where there is a disconnection between the brain and the articulators.

Purpose

•Investigate the coarticulatory and temporal patterns of single syllabic non-words produced by a normal speaker and a speaker with apraxia of speech .

• Coarticulation: the concept that the articulators are constantly moving into position for other segments over a stretch of speech (Articulatory and Phonological Impairments: A Clinical Focus).

Main Focus

•Aim to see whether there are reduced coarticulation patterns in the production of non-word syllables.

Subjects• 2 subjects :

1. AD : severe apraxia of speech2. RM: control subject with normal speech

- Both subjects were 48 year old police officers

- Both subjects were from South Yorkshire* Investigators wanted subjects to have

similar regional accents

- Both subjects were from similar socioeconomic statuses

Data• Subjects were asked to repeat 22 monosyllabic CV or

CVC non-words following an experimenter.

• Speech stimuli were recorded for both subjects.

• Once plotted, the data showed the second subject had stepper slopes in all cases compared to the first subject.

• Researchers linked that to more coarticulation for the control speaker and reduced articulation for the speaker with apraxia.

• Additional data was collected on coarticulation with schwa patterns, and it replicated the same results from the previous findings.

Results

•Reduced coarticulation and lengthened durational patterns in the data of the speaker with apraxia of speech.